1. Field of the Invention
The present invention relates to article carrying apparatuses.
2. Description of the Related Art
Conventionally, various types of article carrying apparatuses (hereinafter, referred to as “parts feeders”), such as vibration-,rotation-, oscillation-, and belt-type parts feeders, for aligning articles such as bulk components while carrying them, and supplying the articles one at a time, have been proposed. Among these, vibration-type parts feeders are the most common.
A vibration-type parts feeder is an apparatus configured so as to align and carry articles placed on a face that vibrates by utilizing the phenomena of relative sliding and jumping between the articles and the face.
FIG. 14 shows an example of such a vibration-type parts feeder. This vibration-type parts feeder 51 includes a base 52, a bowl 54 that is disposed above the base 52 with a predetermined spacing, a plurality of a pair of support springs 53 that is provided between the base 52 and the bowl 54 and that elastically supports the bowl 54 above the base 52, and an electromagnet 56 that is provided on the base 52 and that can attract the bowl 54.
In the vibration-type parts feeder 51 having such a configuration, when an AC voltage at a predetermined frequency is applied to the electromagnet 56, the bowl 54 vibrates corresponding to that frequency, and with this vibration of the bowl 54, articles 57 accommodated in the bowl 54 are carried while being aligned, and supplied one at a time from a gate 55.
With the vibration-type parts feeder 51 having the configuration as described above, there are various problems such as the followings: it takes time and effort to adjust the components; the articles 57 are magnetized; and noise is generated. In particular, the problem of noise is inevitable because the articles 57 are carried while jumping with respect to the bowl 54.
On the other hand, in order to address the problems as described above, various types of vibration-type parts feeders in which a cam mechanism is used as the drive source have been proposed. For example, a vibration-type parts feeder described in JP S63-24891B includes a bowl that is supported so as to be rotationally movable around the central axis, and a cam mechanism that causes the bowl to perform horizontal, rotational vibration with a large difference in the acceleration between the forward movement and the backward movement, and is configured so that articles in the bowl are carried by the friction and the inertial force working in cooperation.
In the vibration-type parts feeder like this, since, for example, the cam mechanism is used and the articles do not jump on the bowl because the bowl oscillates only in the horizontal direction and does not reciprocate in the vertical direction, the problem of generation of noise can be eliminated.
However, in the vibration-type parts feeder having such a configuration, since the bowl oscillates only in the horizontal direction and does not reciprocate in the vertical direction, the articles on the bowl are constantly in contact with the bowl with a predetermined force because of the effect of gravity. Thus, the articles on the bowl cannot be carried efficiently. Moreover, since correct and stable operation cannot be achieved, the articles cannot be carried accurately (see JP S63-24891B, for example).
In general, in order to carry the articles on the bowl, it is preferable that the contact pressure of the articles with respect to the bowl is different between when the bowl moves in the carrying direction of the articles and when the bowl moves in the reverse direction from the carrying direction. That is, it is preferable that when the bowl moves in the carrying direction of the articles, the articles are brought into contact with the bowl with a strong force, thereby inhibiting sliding of the articles with respect to the bowl and carrying them forward, and conversely, when the bowl moves in the direction opposite to the carrying direction of the articles, the articles are brought into contact with the bowl with a slight force, thereby promoting sliding of the articles with respect to the bowl and inhibiting them from returning to the direction opposite to the carrying direction.